mailcow

mailcow is an open-source Docker-based groupware and email suite built from established components including Postfix, Dovecot, Rspamd, SOGo, Redis, MariaDB, Nginx, and Unbound. Its main advantage is a modern admin UI around a full mail-server stack.

Growth work lives or dies on targeting and measurement. What matters is whether behavioral triggers can be built without engineering time, whether the event stream supports attribution past the open, and whether deliverability holds when broadcast volume shares a reputation with product email.

Against behavior-triggered journeys, broadcasts, and winback campaigns measured on revenue, mailcow covers event stream, the suppressions API, and multi-tenant support, and does not cover scheduling. Whether that gap matters depends on how central those are to the build.

• Scheduling: No
• Event stream: Yes
• Deliverability: Self-hosted deliverability depends on DNS, IP history, spam controls, and operator discipline. mailcow bundles Rspamd, DKIM support, quarantine controls, and administration UI around the stack.
• Operating since: Not published
• Suppressions API: Yes
• Best published rate per 1,000: Tiers not published in comparable form
• Multi-tenant: Yes
• Free tier: Free self-hosted, GPL-3.0
• Starts at: Free self-hosted

Self-hosted deliverability depends on DNS, IP history, spam controls, and operator discipline. mailcow bundles Rspamd, DKIM support, quarantine controls, and administration UI around the stack.

Teams that want to self-host a full email and groupware suite.

Small product teams trying to avoid mail-server operations.